Turing tar-pit

1. A place where anything is possible but
nothing of interest is practical. Alan Turing helped lay the
foundations of computer science by showing that all machines and
languages capable of expressing a certain very primitive set of
operations are logically equivalent in the kinds of computations
they can carry out, and in principle have capabilities that differ
only in speed from those of the most powerful and elegantly
designed computers. However, no machine or language exactly
matching Turing's primitive set has ever been built (other than
possibly as a classroom exercise), because it would be horribly
slow and far too painful to use. A `Turing tar-pit' is any
computer language or other tool that shares this property. That
is, it's theoretically universal -- but in practice, the harder
you struggle to get any real work done, the deeper its inadequacies
suck you in. Compare bondage-and-discipline language. 2. The
perennial holy wars over whether language A or B is the "most
powerful".

Probably the most well-known (and also the most painful) real implementation of a turing tar-pit is brainfuck. Some would claim INTERCAL is one too, but many would disagree since INTERCAL goes out of its way to make programming as hard as possible (roman numerals for I/O, that sort of thing).

Another fine example of a turing tar-pit, although in the domain of functional programming languages, is Unlambda.